DE102017124724A1 - Method for producing a vehicle component - Google Patents

Abstract

A method of continuously producing a vehicle component from a sheet metal is to be characterized by the following steps: heating the sheet, separating and / or forming the sheet to obtain a vehicle component, cooling the vehicle component

Description

Technical area

The invention relates to a method and a device for producing a vehicle component according to the independent claims.

State of the art

Vehicle components, in particular shift forks as components of vehicle transmissions, are well known from the prior art.

Furthermore, methods and apparatus for the production of shift forks are known, for example from DE 10 2014 104 610 A1 , According to the DE 10 2014 104 610 A1 the production of a shift fork, by first a bolt and a base body are made by forming, the bolt and the body are then joined by joining, wherein a Schaltgabelvorform arises, which is then forged by forming the shift fork blank and this is subsequently reworked.

The manufacture of shift forks is not limited to the aforementioned forging process. Shifter forks can be cast from steel, aluminum or brass or welded from stamped or finely cut sheet metal parts into an assembly (ZSB).

The production of shift forks relates not only to forging and casting, but also on the one hand to the production of sheet-metal assemblies, which are known from the prior art, and on the other hand on sheet metal wire assemblies and wire-wire assemblies , The latter modules are for example from the DE 10 2013 107 890 A1 and the DE 10 2008 064 221 A1 known. The three aforementioned module variants usually include the assembly of individual components to form an assembly by means of joining methods. Fork and stiffening plate or stiffening wire thereby form the assembly of a shift fork. There are also sheet metal forks, which consist only of a sheet without stiffening.

Object of the invention

The present invention is based on the object to provide an improved method for producing a vehicle component, in particular a shift fork.

Solution of the task

To achieve the object, the features according to the independent claims. Advantageous embodiments are described in the subclaims.

It has been found that the known methods either in terms of a manufacturing effort, i. in the manufacture of the assembly of the individual parts, or in terms of component properties, such as a cast structure, have disadvantages. Vehicle components are designed to be as light as possible in order to keep the vehicle weight as low as possible.

Vehicle components, which are made of sheet metal, but can not be designed arbitrarily easy, since sheets have a uniform wall thickness and a change in wall thickness, for example, by embossing in a cold forming, encounters a limit of Umformvermögens of the sheet. Furthermore, when pressing the sheet high pressing forces are required, which in turn leads to high acquisition costs of machines used for embossing.

In addition to the production described above from sheet metal, it is also known to manufacture vehicle components from castings or castings. Here, gradients of wall thicknesses of the vehicle components are often designed functionally. Since the cast structure of the material can reach the limits of durability, castings or castings made vehicle components are usually backed up, which in turn leads to a higher weight compared to an ideal design of the vehicle component.

The production process according to the present invention combines the advantages of the manufacturing processes described above. On the one hand, a monolithic design is given. On the other hand, the vehicle components, which were produced by the inventive method, have a uniform and uninterrupted fiber flow, which positively influences their fatigue strength.

The present invention is described below exclusively with respect to shift forks. However, the device according to the invention, the method according to the invention and the use according to the invention can be transferred to other vehicle components or used analogously. This may be thought of components for a chassis and a body as well as discs and pinions. Furthermore, vehicle components may also be intended for a housing and a supporting structure.

In the inventive method for the production of vehicle components is a continuous production process for the production of individual parts or individual vehicle components, starting with the heating of the starting material, in particular a sheet on the hot forming and separation from the tape / board to the cooling. Thus, this process is fundamentally different from processes for the continuous production of long products such as tapes, profiles and wires. The latter long products are semi-finished products which are used as starting material for further production processes for the production of individual parts.

In the context of the present invention, a single vehicle component is preferably meant when it comes to vehicle components. Accordingly, in the preferred embodiments is preferably thought of individual shift forks or shift fork items when talking of shift forks.

1. a. Erwärmen des Blechs,
2. b. Trennen und/oder Umformen des Blechs, um eine Schaltgabel zu erhalten
3. c. Abkühlen der Schaltgabel.

The method according to the invention for producing a shift fork from a metal sheet comprises the following steps:

1. a. Heating the sheet,
2. b. Separating and / or forming the sheet to obtain a shift fork
3. c. Cool down the shift fork.

Preferably, the aforementioned steps follow a. to c. in the order shown continuously on each other.

It may be thought of performing one or more separation and / or forming steps in parallel or in succession.

The separation and / or reshaping can be followed by a calibration. Preferably, the calibration is performed after step b. and before step c, wherein all steps preferably follow each other continuously.

1. a. eine Einrichtung zum Erwärmen des Blechs,
2. b. eine Einrichtung zum Trennen und/oder Umformen des Blechs, um eine Schaltgabel zu erhalten sowie
3. c. eine Einrichtung zum Abkühlen der Schaltgabel.

An apparatus according to the invention for producing a shift fork from a sheet metal

1. a. a device for heating the sheet,
2. b. a device for separating and / or forming the sheet to obtain a shift fork and
3. c. a device for cooling the shift fork.

The device is set up to enable continuous production of the vehicle component. Details are described below, also with regard to the inventive method.

In a device for separating and / or forming the sheet may be a punching system. The device for separating and / or forming the sheet metal, in particular the punching machine, can have a press, in particular a servo-controlled hydraulic press.

The device for separating and / or forming the sheet can be equipped with separating and / or forming tools. These may be progressive tools and / or transfer tools. The sheet to be machined can therefore be processed in follow-on composite operation and / or in transfer mode.

The means for heating the sheet may be an oven. The furnace is preferably connected upstream of the device for separating and / or forming the sheet metal. The oven is used, for example, to heat the sheet to forming temperature.

Further, the means for heating the sheet may include an inductor and, optionally, a downstream furnace section.

The apparatus may further include means for calibrating to calibrate the sheet after separation and / or forming.

By the sheet is heated before forming, significantly higher degrees of deformation can be achieved than for example during cold forming. Thus, even complex shift forks in only one step chain including heating of the sheet as well as cutting and / or forming can be produced, which must be joined according to the prior art, for example, of several individual parts. Also, the separation is easy if the sheet was previously heated. By heating prior to cutting and / or forming, sophisticated geometry shift forks, such as T- or L-profile shift forks and / or shift forks with variable i. not at every point of the shift fork identical wall thickness can be produced inexpensively. Since an interpretation of both the wall thickness and a profile shape of modern shift forks based on forces that are to be transmitted from or to the shift fork, nowadays, shift forks often have sophisticated geometries.

A variable wall thickness can be achieved by thickening or reduction. The reduction can be effected by upsetting. The thickening can be effected by pulling through are produced, which are subsequently compressed.

By heating, lower forming and pressing forces must be applied compared to prior art methods. Furthermore, the variety of shapes is increased over known methods, so it can be made a wider range of different types of shift forks. As is known, the torsional rigidity of T and L profiles is higher in comparison, for example, with flat metal sheets. While reinforcing plates or the like had to be welded to the shift fork or to its base body in known methods for producing shift forks, this is not necessary in the method according to the present invention. The heating before separating and / or forming as described above allows the production of shift forks, which for example by thickening and / or compression have a variable wall thickness, for example the same or similar to a T or L profile. In contrast to known production methods, the present method thus allows the production of shift forks with the same torsional rigidity without having to weld reinforcing plates or the like.

Furthermore, the method according to the invention allows the component properties of the shift forks, in particular their strength, to be adjusted in a targeted manner.

Furthermore, according to the method according to the invention, particularly light and strong shift forks can be produced by using a steel material for the production.

By means of a calibration step which can be integrated within the process chain or a calibration, an improvement in the tolerance of the deformed shift forks can be achieved. A tolerance of the shift fork is understood their permissible deviation from their Nenmaß.

If, according to the present invention, the separation and / or forming is carried out after the heating, the tolerances achieved are higher than, for example, during cold forming. The shift forks thus deviate more strongly from the nominal size, if the sheet was heated before separation and / or forming. By calibrating or the calibration step after the separation and / or reshaping, the deviation from the nominal dimension can be reduced and the tolerance can thus be improved or reduced.

For the purposes of the present invention, calibration is understood to mean a downstream forming step for the post-processing of sections or regions of a component, in particular for reducing the deviation from the nominal dimension.

The sheet may in this case be heated to a temperature above its recrystallization temperature, so that recrystallization takes place before the cooling of the shift fork. This can be done, for example, by soft annealing or normalizing. Recrystallization gives the fork to be produced homogeneous component properties and a uniform structure. Furthermore, the recrystallization makes it possible for the sheet metal used as the starting material to be both cold-rolled and hot-rolled.

The heating of the sheet to a temperature above its recrystallization temperature and subsequent forming are summarized as hot working. In contrast to forming at lower temperatures, hot forming is characterized by an easier formability and a higher forming capacity. Thus, lower forces are required for forming and higher degrees of deformation can be achieved.

The sheet may also be heated to a temperature below its recrystallization temperature, for example to 600 ° C. Such heating and subsequent forming are collectively referred to as warm forging. Similar to hot forming and in contrast to cold forming, warm forging is characterized by its easier formability and high formability. Furthermore, the hot forging also provides advantages of cold forming, for example high accuracy. In addition, higher strengths can be achieved in hot forging than in cold forming. By guiding and controlling the cooling, it is possible to set specific strengths and thus specific component properties.

After heating, a first removal of impurities, in particular a first descaling, take place.

The removal of contaminants can be done in any way. For example, it may be intended to air pressure or at least one liquid jet, in particular to at least one water jet, with which a surface of the sheet is freed of impurities. In particular, descaling may be intended to remove iron oxide-containing surface contaminants from water which is applied to the panel at high pressure.

After cooling, a second descaling and / or a cleaning and / or a Preserve take place. The second descaling may be carried out in the same manner as described above for the first descaling. The cleaning and preserving can be done in any known ways.

The sheet can be present as a board or as a coil. As a board, also sheet metal plate, single board, sheet metal plate or Blechabwicklung called a flat sheet metal section is called in the unbent or unprocessed state. As a coil or collar, a sheet is called in the wound state. Preferably, in the context of the present invention, thick sheets with a wall thickness of 3 to 25 mm, more preferably 5 to 12 mm are intended.

Regardless of whether the sheet is present as a board or coil, it is preferably supplied continuously to the device for heating.

It is particularly advantageous if the above-described process steps are continuously successive, i. be carried out immediately after each other. This applies to all process steps, i. also for the optional steps. Thus, the sheet, in particular if it is present as a coil, heated continuously, optionally descaled for the first time and subsequently a device for separating and / or forming the sheet, in particular a punching system are supplied. After that, an optional calibration can be connected before the individual vehicle component cools down. Subsequently, a second descaling can optionally take place. Within the process sequence under hot forming conditions, the continuously manufactured individual vehicle component undergoes a targeted change from stage to stage or from process step to process step, so that one final vehicle individual part leaves the continuous production line per stroke.

In the device for separating and / or forming the sheet metal or the punching system, a multi-stage partial reshaping and / or punching can take place in the follow-on composite. In this case, a partial deformation is understood to mean that the transformation to be carried out is subdivided into a plurality of sub-steps and implemented at different component regions. When processing in the follow-on composite, the (partially) formed individual vehicle component is still connected to the metal sheet. After the individual vehicle component has been separated from the metal sheet, further forming and / or punching steps can take place in the aforementioned device in the transfer mode. After that, an optional calibration can be added. Subsequently, the vehicle individual components are supplied to a cooling. All process steps should take place within a continuous process chain, since such a continuous process chain brings numerous advantages.

The process steps separating and hot forming and the subsequent cooling process are to be considered separately from each other in known batch processes. The component temperature required for the cooling process must take place before each of the mentioned method steps by heating the individual vehicle component, because the individual vehicle components cool down in the interim during discontinuous process sequences. In the present continuous process, one-time heating is sufficient because the process steps requiring heated vehicle individual parts and a heated sheet, respectively, are performed immediately after each other, so that the sheet or vehicle single-component can be processed from the process heat to the end of the process chain.

Furthermore, in a continuous process over known discontinuous processes numerous laborious, time-consuming and expensive steps can be omitted since they are no longer needed. For example, once the individual vehicle components are no longer connected to the metal sheet, they can be separated after each method step and fed to the next method step.

By separating after each step and feeding to the next step, a complex logistics is unnecessary. There is no need for removal or storage space. It is also possible to monitor dimensions of the individual vehicle components.

This allows an immediate recognition of production errors as well as an immediate sorting out of defective individual vehicle components. Faulty individual vehicle components are thus not supplied to further process steps, which in turn saves costs, time, energy and material, since the defectiveness of the individual vehicle component is not recognized until after the last method step.

It is also possible with this monitoring option, a correction of errors within the production line of individual vehicle component to vehicle single component in-line. The automatable production within predetermined tolerance limits is realizable according to this invention for the continuous production of hot-formed individual vehicle components.

After at least one separation and / or forming step has taken place, in which a sheet or a sheet metal part is separated from the coil, can also be thought to promote this separate from the coil sheet or sheet metal part separately and to to edit. For example, a shift fork can be punched out of the coil and then fed to the device for cooling the shift fork.

The separation of the sheet can be done by any separation method. In particular, can be thought of any cutting operations as well as a punch.

• - ein Prägen
• - ein Biegen

durchgeführt werden. Ferner kann auch an ein Tiefziehen, ein Durchsetzen, ein Stauchen sowie an ein Fliesspressen gedacht sein.The forming of the sheet can after at least one of the forming processes

• - an embossing
• - a bending

be performed. Furthermore, it can also be thought of deep drawing, penetration, upsetting and extrusion.

It may be thought to bring the sheet to a temperature above its temperature Ac1. Ac1 denotes a known from the prior art holding or break point in a cooling curve of a material, in particular a metallic material, and thus by a transformation temperature. Here "A" stands for "arrêt", ie the breakpoint, and "c" for "chauffage", ie a warming. The transformation temperature Ac1 is thus specific for the heating of the material. Such temperatures can be found in monographs on material properties of materials and familiar to the skilled person or at least accessible.

If the sheet cools in the means for separating and / or forming the sheet after heating to a temperature below the temperature Ac1, the separation and / or forming is nevertheless possible, although the separation and / or forming at temperatures above the temperature Ac1 is often more advantageous.

It may be intended to continuously heat the sheet or to design the means for heating the sheet as a continuously operated device, for example as a continuously operated inductor. This is particularly advantageous if the sheet is present as a coil and continuously unwound or supplied to the device for heating.

It may be thought to follow the means for heating a balancing section to ensure that there are no temperature differences in the sheet as it enters the means for separating and / or forming the sheet. The balancing section can ensure this in any way. For example, it may be thermally insulated and / or have suitable means for heating and / or temperature maintenance means.

The separation and / or forming can be carried out with preheated separating and / or forming tools. By preheating the cutting and / or forming tools on the one hand stress cracks in the tool can be avoided, which can occur at large temperature differences between the tool and the workpiece or sheet. On the other hand, by preheating a thermal expansion of the tool can be considered and effected before the start of processing of the workpiece or sheet. The preheating can be accomplished by a heating system in the tool or by the production of so-called Einfahrteile until reaching a target temperature of the tool to be reached in the context of preheating. To avoid overheating of the tool cooling channels can be incorporated in the tool. Such a preheating and the aforementioned cooling channels are known from the prior art.

The temperature of the tools may be selected so that the temperature of the sheet to be machined during separation or during forming is always above the recrystallization temperature or above the temperature Ac1.

It may be thought to perform a heat treatment of the shift fork after the heating as well as the cutting and / or forming in order to influence their component properties, for example, to increase their strength.

The sheet metal can consist of a weldable steel or non-ferrous material.

The cooling can be done by placing the shift fork on a cooling belt and then air cooling on the cooling belt or by inserting the shift fork in a water or oil bath.

The cooling of the shift fork can be done by a high-temperature mechanical treatment. In this case, the cooling is preferably carried out very quickly.

1. a. eine Einrichtung zum Erwärmen eines Blechs,
2. b. eine Einrichtung zum Trennen und/oder Umformen des Blechs sowie
3. c. eine Einrichtung zum Abkühlen und Entzundern des Werkstücks

kann erfindungsgemäss zur kontinuierlichen Herstellung einer Schaltgabel verwendet werden.A device for producing a workpiece comprising

1. a. a device for heating a sheet,
2. b. a device for separating and / or forming the sheet metal as well
3. c. a device for cooling and descaling the workpiece

can be used according to the invention for the continuous production of a shift fork.

The continuous production has been described above with particular regard to the inventive method.

The device may also have a means for calibration.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102014104610 A1 [0003]
• DE 102013107890 A1 [0005]
• DE 102008064221 A1 [0005]

Claims (16)

Method for producing a vehicle component from a metal sheet, characterized by the following steps: a. Heating the sheet, b. Separating and / or forming the sheet to obtain a vehicle component c. Cooling of the vehicle component, the steps follow each other continuously. Method according to Claim 1 , characterized in that the separation and / or reshaping followed by a calibration. Method according to one of the preceding claims, characterized in that it is the vehicle component is a shift fork. Method according to one of the preceding claims, characterized in that after the heating, a first removal of impurities, in particular a first descaling takes place. Method according to at least one of the preceding claims, characterized in that after cooling a second descaling and / or cleaning and / or preserving takes place. Method according to at least one of the preceding claims, characterized in that the sheet is present as a board or as a coil. Method according to at least one of the preceding claims, characterized in that the separation of the sheet takes place by a cutting process or by a punch. Method according to at least one of the preceding claims, characterized in that the forming of the sheet is carried out according to at least one of the forming methods - embossing - bending - upsetting - deep drawing - penetrating - extrusion. Method according to at least one of the preceding claims, characterized in that the sheet is brought to a temperature above its temperature Ac1. Method according to at least one of the preceding claims, characterized in that the separation and / or forming is carried out with preheated separation and / or forming tools. Method according to at least one of the preceding claims, characterized in that the sheet consists of a weldable steel or non-ferrous material. Method according to at least one of the preceding claims, characterized in that the cooling takes place by depositing the vehicle component on a cooling belt or by inserting the shift fork in a water or oil bath. Method according to at least one of the preceding claims, characterized in that the cooling of the vehicle component takes place by a high-temperature mechanical treatment. Device for producing a vehicle component from a metal sheet, characterized by a. means for heating the sheet, b. a device for separating and / or forming the sheet to obtain a vehicle component and c. a device for cooling the vehicle component, wherein the device is configured to enable a continuous production of the vehicle component. Device according to Claim 14 , characterized in that it is the vehicle component is a shift fork. Use of a device for producing a workpiece comprising a. a device for heating a sheet, b. a device for separating and / or forming the sheet metal as well c. a device for cooling the workpiece for the continuous production of a vehicle component, in particular for the continuous production of a shift fork.